Improved removal/reduction of soils and/or stains (e.g., organic stains), whiteness maintenance, and/or clay suspension are desirable properties for laundry detergents and cleaning compositions. Typically, the wash water used with laundry detergents or cleaning compositions, may contain naturally occurring contaminates (e.g., calcium, iron, barium, bicarbonate, carbonate, oxide, oxylate, sulfate, phosphate, zinc, etc.) that chemically combine in the wash to form insoluble precipitates. Additionally, the wash water may contain insoluble contaminates (e.g., clay, silica, iron oxides, etc.) that can settle out of water and deposit on the fabric article and/or various surfaces of the material being cleaned, during the wash. These precipitates and inert materials can collect on fabric and material surfaces to form residues and/or deposits, thereby negatively impacting its whiteness appearance, and hence overall cleaning performance.
Additionally, the current market demands are for laundry products and cleaning compositions with improved environmental sustainability (e.g., elimination of phosphate builders) and/or energy savings (e.g., formulated for re-used wash water, for example, re-used water in bathtub) without negatively impacting cleaning performance (e.g., whiteness maintenance, stain removal, anti-soil redeposition, etc.). This, of course, brings additional challenges since re-used wash water tends to have disadvantages, for examples, increased soil components to fabric/materials in the re-used wash water, and elevated water hardness levels as a result of, for example, repeated heating.
Under high water hardness condition, anionic surfactants bind with the more readily available calcium and/or magnesium ions to reduce cleaning performance (i.e., reduce deposition inhibiting ability and stain removal). Flocculation of soil particles also tends to proceed readily in elevated water hardness conditions and leads to graying of the fabric/material from redeposition of soils. In particular, the decrease in whiteness will become more dramatic over multi-cycle washes.
Further, there are practical challenges of providing sufficient cleaning performance for certain consumer wash behaviors, for example, dilute wash conditions due to insufficient amounts of laundry detergent or cleaning composition and/or excessive water volume have been used. Both cost constraints and loading capacity limitations mean that ever increasing levels of detergent ingredients or cleaning actives into the formulated laundry product or cleaning composition is not a viable option, but instead, further improvements are needed to meet these needs.
Typically, acrylate polymers have been useful as an effective dispersants for suspension and removal of particulates. For example, Acusol 445™ (Rohm and Haas), a homopolymer of acrylic acid having a molecular weight of 4,500 g/mol, delivers cleaning benefits by absorbing to the charged soil surface, through its acrylate functionality, for removal of the soil from the wash water. However, Acusol 445™'s low molecular weight is insufficient to impart any significant steric stabilization of primary soil particles in the wash water to prevent aggregation of the soil particles.
Other examples of conventional carboxyl group-containing polymers are disclosed in PCT Publications WO2007/089001, Yoneda, A. et al., and JP-A 2009-28618, Nakano et al. WO '001 describes a (meth)acrylic acid-based copolymer that includes 70% to 95 mol % of a structure unit (a) derived from a (meth)acrylic acid-based monomer (A) and 5% to 30 mol % of a structure unit (b1) derived from a (meth)allyl ether monomer (B1) and terminated with a sulfonic acid group at one or both ends of its main chain. WO '001 states that their (meth)acrylic acid-based copolymer exhibits excellent chelating ability, dispersibility, and gel resistance.
JP '618 describes a scale inhibitor that contains a (meth)acrylic acid-based polymer including a structure unit (a) derived from a (meth)acrylic acid-based monomer (A), a structure unit (b) derived from a sulfonic acid-based monomer (B), and a structure unit (c) derived from another (meth)acrylic acid-based monomer (C). According to JP '618, the (meth)acrylic acid-based polymer has an excellent capacity to inhibit scale of calcium phosphate.
Both patent applications fail to identify the problems associated with washing under elevated water hardness levels, particularly in the case of re-used wash water, and hence did not recognize the need for polymers with improved anti-soil redeposition and whiteness maintenance benefits. Furthermore, the polymers of WO '001 are designed for the dual purpose of removal of hydrophobic stains (e.g., collar or greasy dirt) and prevention of redeposition of hydrophilic soils (e.g., clay), so therefore those polymers are unlikely to have sufficient improved performance against muddy soils, particularly in elevated water hardness conditions. As for JP '618, it is focused on development of polymers for use as scale inhibitors, which typically is optimized for carboxylic acid containing polymers having molecular weights below 20,000 (see Amjad, Z, Tenside Surf Det. 42 (2005), 2), while the polymers of the current application has a weight average molecular weight of from about 23,000 to about 50,000.
One way to improve functionality is through modification with non-ionic monomers to ensure sufficient steric stabilization, while sulfonation is another way to impart more electrostatic stabilization once the polymers absorbs onto the soil surface. PCT Publications WO2010/024448, Yoneda, A., et al., and WO2010/04468, Dupont, J. S., et al., describe carboxyl group-containing polymers as hydrophobic group-containing copolymers comprising certain molar ratios of: (i) an ether bond-containing monomer, (ii) a carboxylic group-containing monomer, and (iii) a sulfonic acid group-containing monomer; and having an average molecular weight range of 2,000-200,000, to reduce/prevent surfactant precipitation. However, neither application disclose any preferred molecular weight ranges for the polymers useful for improved soil and stain removal, whiteness maintenance, and/or clay suspension, preferably when formulated in products for use in dilute and high water hardness wash conditions.
Therefore, not all conventional carboxyl group-containing polymers and compositions containing these polymers meet the recent need, that is, high performance in aqueous environment. Therefore, further improvements are required to provide laundry detergents and cleaning compositions comprising polymers suitable to meet the challenge of environmental sustainability and/or energy efficiency.
Accordingly, there is a need for a laundry detergent or cleaning composition having superior cleaning performance than what has existed before. In particular, the laundry detergent or cleaning composition having improved anti-soil redeposition and/or whiteness maintenance, sufficient to prevent soil particles and/or aggregates from reattaching to fabric/material surfaces being washed, preferably hard water wash conditions and/or over multi-cycle washes.
The need also exist for a laundry detergent or cleaning composition having improved soil or stain removal benefit, preferably effective on organic stains.
It is also desirable that the laundry detergent or cleaning composition having sufficient cleaning performance across a range of consumer wash habits, for example, dilute wash conditions and/or use of recycled wash water.